- A. Marcus & E Webers (eds). Zeitschrift fűr sexual Wissenschaft. XVI (1929-30): 45. Cited in Vern L. Bullough & Bonnie Bullough. Cross Dressing, Sex, and Gender. University of Philadelphia Press 1993: 275n7.
Bullough gives Toni’s name as “Toni Claus Hans F. Den Antrag” which seems to be a conflation of her female name, her male name and the German word ‘Antrag’ which means 'application'. DE.Wikipedia does not feature any persons at all with the surname Den Antrag.